Water is highly utilized in cooling water systems, water systems in manufacturing processes of paper and pulp, water systems for collecting dusts and scrubber water systems due to insufficient water resources. For example, the amount of forced blow is decreased in the highly concentrated operation of open circulation cooling water systems. When water is highly utilized as shown in the above example, the quality of water is lowered due to concentration of dissolved salts and nutrients and slime is formed from a mixture containing microorganisms such as bacteria, fungi and algae, sand and dusts. When slime is formed, the heat efficiency in heat exchangers decreases and the flow of water is suppressed. Local corrosion of instruments and pipings takes place at portions covered with the attached slime.
To prevent troubles caused by slime such as those described above, utilization of various antimicrobial agents has been proposed. For example, in Japanese Patent Application Publication No. Showa 41(1966)-15116, as the process for suppressing growth of microorganisms in the flow of treated water, a process which comprises mixing a solution of a salt of hypochlorous acid and a solution of a salt of sulfamic acid to react these compounds and form a solution of a reaction product comprising a salt of N-chlorosulfamic acid, and supplying the formed solution into an aqueous flow for treatment, is disclosed. As higher utilization of cooling water further proceeds, the troubles caused by slime also increase further and it is required that an antimicrobial agent be added in a higher concentration. However, when an oxidative antimicrobial agent is used, it is difficult that the concentration of the added agent is increased since the possibility of corrosion of metals increases. Moreover, since the oxidative antimicrobial agent exhibits poor penetration into slime although the oxidizing ability is great, it is difficult that the troubles caused by slime are suppressed once the troubles take place.
In Japanese Patent Application Laid-Open No. Heisei 7(1995)-206609, taurine chloramine and others are proposed as novel bactericides containing a compound having halogen and nitrogen as the effective component. Since organic bactericides have a small or no oxidizing ability and exhibit strong penetration into slime, it is possible that the troubles caused by slime are suppressed when the troubles take place. However, the spectrum of the effectiveness for the constituting elements of the slime such as bacteria, fungi and algae is different for each selected agent. Moreover, the cost of the agent is far greater than the oxidative antimicrobial agents and the cost of the treatment markedly increases.
Therefore, an agent and a process for preventing formation of slime which are effective for all constituting elements of slime such as bacteria, fungi and algae with a small amount of the agent even under the condition of severe troubles caused by slime and can prevent formation of slime at a low cost, have been desired.